Refrigeration systems comprising an evaporating heat exchanger in which liquid refrigerants such as chlorofluorocarbons, more commonly known as refrigerants, are evaporated to draw heat from another medium such as air or water are well known. A compressor normally serves to circulate the refrigerant and has a low pressure or suction inlet which receives spent refrigerant from an evaporating heat exchanger and a high pressure outlet which discharges compressed refrigerant into a high pressure line. The compressed refrigerant is commonly received by a condensing heat exchanger, transferring heat from the compressed refrigerant to another medium, most commonly air or water. The cooled and condensed refrigerant is then conveyed along the high pressure liquid line to an expansion device which discharges the refrigerant through a narrow orifice into the evaporating heat exchanger, causing an expansion and evaporation of the refrigerant and consequently a cooling effect.
It is essential for proper and efficient operation of such a system that a liquid seal be formed in the high pressure line upstream of the expansion device. Essentially, a liquid must be presented to the high pressure inlet of the expansion device to obtain proper circulation of the refrigerant and effective cooling in the evaporating heat exchanger. This liquid seal is commonly formed at the condensing heat exchanger used to cool the compressed refrigerant, but this tends to reduce the efficiency of operation. In particular what may be described as a solid liquid line or continuous liquid line is formed between the condensing heat exchanger and expansion device, and since the condensing heat exchanger is commonly remotely located from the expansion device itself, this solid liquid line may be quite long, measuring hundreds of feet in many instances. This introduces a large pressure drop along the high pressure line and consequently requires that the compressor be sized to generate an appropriate high pressure differential to accommodate expected line losses. This in turn requires that larger operating currents be supplied to the compressor.
It is not practical in most industrial and commercial applications to locate the compressor and condenser required to cool the compressed refrigerant proximate to the expansion device in order to reduce system circulating losses. Accordingly, it is an object of the invention in one particular aspect thereof to provide an improved refrigeration system in which a liquid seal may be formed a short distance from an expansion device thereby ensuring proper volumetric flow of associated refrigerant while providing more energy efficient circulation of the refrigerant.